💪 Deltoid

Brian Lee

🧑 AI Generated, Human Reviewed

The deltoid is a triangular shoulder muscle that defines the arm’s connection to the torso. Composed of three sections—anterior, lateral (or middle), and posterior—it shapes the shoulder’s contour and shifts visibly with arm movement. This muscle covers the front, side, and back of the shoulder joint, playing a crucial role in shoulder mobility and strength.

The deltoid’s proximal attachment is U-shaped, resembling the distal insertion of the trapezius muscle. Artists often emphasize the deltoid to convey strength, width, and motion in the upper body, as its dynamic changes enhance the realism of the figure.

Summary

Illustrations

Translations

Examples

Diana and Cupid by Pompeo Batoni, 1761

Study Questions

Which of the following is the correct insertion point of the deltoid muscle?

1. Greater tubercle of the humerus
2. Deltoid tuberosity of the humerus
3. Acromion process of the scapula
4. Lateral lip of the bicipital groove

The anterior (clavicular) head of the deltoid originates from which bony landmark?

1. Spine of the scapula
2. Acromion process
3. Lateral third of the clavicle
4. Medial border of the scapula

Which action is primarily performed by the middle (acromial) fibers of the deltoid?

1. Shoulder flexion
2. Shoulder abduction
3. Shoulder extension
4. Shoulder medial rotation

See Also

Arm Movements

References

• Wikipedia
• Richer, Plate 49
• Hale and Coyle 1977
  • 26, 32, 106, 108, 114, 116, 118, 122-123, 126, 128, 130, 132, 134, 138, 144, 146, 148, 150, 152, 182, 250, 251, 253, 254, 255
• Goldfinger 1991
  • 156–58